This 3-year "Longitudinal Study of the RAP Peer Intervention for HIV Prevention" will assess the long-term behavioral effects of a peer-implemented HIV prevention program on trained active drug users and the drug-using contacts to whom they provide intervention, diffusion of the intervention and its effects through drug-user social networks and into drug use sites in Hartford, CT, and sustainabilitv of peer-led HIV prevention intervention. This is a continuation of the (RAP) project (R01 DA13356) to test this theoretically driven peer intervention program regarding its effectiveness in reducing HIV risks and drug-related harm among the trained "Peer Health Advocates" (PHAs), their network Contact Referrals (CRs), and the Hartford drug-using community. The aims of the proposed continuation study are to assess: 1) long-term effects of the RAP PHA training program and the process of delivering the peer-led intervention on PHAs' HIV risk reduction attitudes and behaviors; 2) long-term effects of the RAP PHA delivered peer-led intervention on CRs' HIV risk reduction attitudes and behaviors; 3) the diffusion of the RAP peer-led intervention components (materials, messages), effects (risk/harm reduction practices), and delivery process (peers helping peers) through networks of drug users in Hartford; and 4) the sustainability of the RAP peer-led intervention (materials/messages, risk reduction practices, peer-delivery process), and factors needed to sustain it over time. The study integrates qualitative and quantitative methods to document the process of peer intervention provision in the community and its impact. This will include the following three primary activities over the three-year extension: 1) a repeat follow-up (T3) survey interview with PHAs who initiated the training (n=129; 90 after attrition), their initial Contact Referrals (CR) who we interviewed at the start of the study (n=258, 155 after attrition), and at least one new CR from PHAs' current drug-using social networks (n=90); this survey (total n=335) will be conducted at approximately 2-21/2 years post intake for PHAs and original CRs; 2) continued ethnographic observations of drug use sites and Community Advocacy Group meetings of PHAs, and in-depth interviews of PHAs, CRs, and other drug users regarding the intervention, its provision and effects, and its diffusion and sustainability; and 3) a repeat "communitywide survey" conducted with PHAs, CRs, and other drug users in Hartford, using the same methods as the communitywide survey of the original RAP study (n=700).